1. Field of the Invention
This invention relates to a double chuck type mechanical pencil, and specifically to a double chuck type mechanical pencil and an internal writing mechanism thereof comprising a feed chuck for feeding a normal lead, and a tip chuck for holding a lead at the tip thereof to reduce a residual lead.
2. Description of the Prior Art
The conventional double chuck type mechanical pencil is excellent in that a residual lead is extremely reduced, but the number of parts is larger than that of the normal mechanical pencil and the construction is complicated. Therefore, it takes time to incorporate the parts into a barrel, and the cost is high. In particular, in the assembling step for conventional articles, pressing of a tip spring and an inner barrel has been carried out at a position that cannot be seen from outside within a cap. since in this case, the incorporating work is carried out in a groping state, it takes much time for inspection work after the incorporation.
Further, in conventional articles of this kind, a cap is used as a tip chuck to thereby fix the tip whereby holding of a lead is made positive and stabilized. However, since the tip becomes fixed so that a load applied to a lead becomes concentrated on one point of the tip chuck portion, as a result of which the lead is possibly broken.
This invention overcomes the disadvantages noted above with respect to the conventional double chuck type mechanical pencil as described above. It is an object of the invention to provide a double chuck type mechanical pencil and an internal writing mechanism thereof wherein in the assembling work of parts, an internal writing mechanism is inserted into a barrel as a mechanical pencil body, without directly incorporating parts into a barrel as in prior art, and a cap is screwed from the forward of the barrel or the internal writing mechanism is dropped from the rear of the barrel which is a so-called single shaft, whereby the assembling step is extremely simplified and the parts can be incorporated as a unit in a one-touch manner, thus materially facilitating mass production.
Further, according to this invention, inspection can be made prior to incorporation of an internal writing mechanism in the form of a unit into a barrel. Therefore, an object of the invention is to provide a double chuck type mechanical pencil and an internal writing mechanism thereof wherein the confirmation and inspection time after incorporation is shortened and articles of inferior quality in the form of finished articles can be reduced.
Furthermore, according to this invention, internal writing mechanisms including a tip chuck (a tip ring, a tip spring, a resilient frictional member, a feed chuck, a chuck ring, a chuck spring, an inner tube, a sleeve, a lead tank, a knock unit, etc.) are cushioned whereby a load caused by writing pressure concentrated on one point of a tip chuck portion is absorbed by cushion means so that a lead is hard to be broken and even a user having strong writing pressure can obtain a very smooth and good writing feeling. Therefore, an object of the invention is to provide a double chuck type mechanical pencil and an internal writing mechanism thereof which has a general usability.
For achieving the aforementioned objects, according to this invention, there is provided a double chuck type mechanical pencil comprising a tip chuck for holding a lead at an end opening of a barrel, and a feed chuck provided at the rear of the tip chuck and in which a lead tank is advanced by knocking operation to thereby feed the lead toward the tip chuck, wherein cushion means for absorbing a load caused by writing pressure against the tip chuck is provided at the rear of the tip chuck.
Further, an internal writing mechanism of the double chuck type mechanical pencil according to this invention comprises a lead tank for receiving leads, a feed chuck connected to the lead tank to feed the leads, a chuck ring loosely fitted in the feed chuck, a sleeve provided externally of the feed chuck, a chuck spring provided between the sleeve and the lead tank, an inner tube provided externally of the sleeve and having engaging means between it and the sleeve, a tip chuck fixedly mounted on the end part relative to the inner tube, and a tip spring provided between the tip chuck and the inner tube.
Further, the double chuck type mechanical pencil according to this invention comprises a lead tank provided movably in a longitudinal direction within a barrel, a feed chuck connected to the lead tank to feed a lead, a chuck ring loosely fitted in the feed chuck, a sleeve provided externally of the feed chuck and engaged movably with the barrel, a chuck spring provided between the sleeve and the lead tank, an inner tube provided externally of the sleeve, fitted with the sleeve and is movable integrally, a tip chuck provide at the end part of the inner tube, a tip ring provided externally of the tip chuck, and a tip spring provided between the tip chuck and the inner tube.